The processes which contribute to the perseverence of erroneous personal and social beliefs are investigated in a series of studies. The first set of studies investigates the cognitive mechanisms of biased assimilation and causal explanation which are postulated to be the underlying causes of belief perseverence. A second set of studies examines the behavioral and inferential consequences of judgmental overconfidence and the cognitive mechanisms that underlie it. A third set of studies explores the individual's response to the clash between intuitive theories and the data of immediate or recalled experience.